Organ separation for thermal therapy

ABSTRACT

A method of providing thermal therapy to prostate tissue of a patient. The method includes: inserting a mechanical separator or infusing a fluid to separate human tissue to be treated from nontarget tissue, thereby providing thermal insulation and other beneficial effects, and applying the thermal therapy to the target tissue.

The present invention relates generally to an apparatus and method forperforming a thermal therapy patient treatment protocol. Moreparticularly, the invention relates to a novel apparatus and method forphysically separating organs to enable aggressive thermal therapy to beadministered safely and relatively comfortably, on an outpatient basis,if desired.

Thermal therapy has been proven to be an effective method of treatingvarious human tissues. Thermal therapy includes tissue freezingthermotherapy, hyperthermia treatment and various cooling treatments.Thermotherapy treatment is a relatively new method of treatingcancerous, dieseased and/or undesirably enlarged human prostate tissues.Hyperthermia treatment is well known in the art, involving themaintaining of a temperature between about 41.5° through 45° C.Thermotherapy, on the other hand, usually requires energy application toachieve a temperature above 45° C. for the purposes of coagulating thetarget tissue. Tissue coagulation beneficially changes the density ofthe tissue. As the tissue shrinks, forms scars and is reabsorbed, theimpingement of the enlarged tissues, such as an abnormal prostate, issubstantially lessened. Further, tissue coagulation and its beneficialeffects are useful for treating cancerous tissue, because cancer cellsare particularly susceptible to abnormal temperatures. Cancer cells canbe treated in accordance with the present invention with temperatures inexcess of 100° C. without damage to the therapy applicator or discomfortto the patient.

The higher temperatures required by thermotherapy require delivery oflarger amounts of energy to the target prostate tissues. At the sametime, it is important to protect nontarget tissues from the highthermotherapy temperatures used in the treatment. Providing safe andeffective thermal therapy, therefore, require devices and methods whichhave further capabilities compared to those which are suitable forhyperthermia.

Although devices and methods for treating prostate cancer and benignprostatic hyperplasia have evolved dramatically in recent years,significant improvements have not occurred and such progress is badlyneeded. As recently as 1983, medical textbooks recommended surgery forremoving cancerous or impinging prostatic tissues and four differentsurgical techniques were utilized. Suprapubic prostatectomy was arecommended method of removing the prostate tissue through an abdominalwound. Significant blood loss and the concomitant hazards of any majorsurgical procedure were possible with this approach.

Perineal prostatectomy was an alternatively recommended surgicalprocedure which involved gland removal through a relatively largeincision in the perineum. Infection, incontinence, impotence or rectalinjury were more likely with this method than with alternative surgicalprocedures.

Transurethral resection of the prostate gland has been anotherrecommended method of treating benign prostatic hyperplasia. This methodrequired inserting a rigid tube into the urethra. A loop of wireconnected with electrical current was rotated in the tube to removeshavings of the prostate at the bladder orifice. In this way, noincision was needed. However, structures were more frequent and repeatoperations were sometimes necessary.

The other recommended surgical technique for treatment of benignprostatic hyperplasia was retropubic prostatectomy. This required alower abdominal incision through which the prostate gland was removed.Blood loss was more easily controlled with this method, but inflammationof the pubic bone was more likely.

With the above surgical techniques, the medical textbooks noted thevascularity of the hyperplastic prostate gland and the correspondingdangers of substantial blood loss and shock. Careful medical attentionwas necessary following these medical procedures.

The problems previously described led medical researchers to developalternative methods for treating prostate cancer and benign prostatichyperplasia. Researchers began to incorporate heat sources in Foleycatheters after discovering that enlarged mammalian tissues respondedfavorably to increased temperatures. Examples of devices directed totreatment or prostate tissue include U.S. Pat. No. 4,662,383 (Harada),U.S. Pat. No. 4,967,765 (Turner), U.S. Pat. No. 4,662,383 (Sogawa) andGerman Patent No. DE 2407559 C3(Dreyer). Though these referencesdisclosed structures which embodied improvements over the surgicaltechniques, significant problems still remained unsolved.

Recent research has indicated that cancerous and/or enlarged prostateglands are most effectively treated with higher temperatures thanpreviously thought. Complete utilization of this discovery has beentempered by difficulties in protecting rectal wall tissues fromthermally induced damage. While shielding has been addressed in somehyperthermia prior art devices, the higher energy field intensitiesassociated with thermotherapy necessitate devices and methods havingfurther capabilities beyond those suitable for hyperthermia. Forexample, the microwave-based devices disclosed in the above-referencedpatents have generally produced relatively uniform cylindrical energyfields. Even at the lower energy field intensities encountered inhyperthermia treatment, unacceptably high rectal wall temperatures havelimited treatment periods and effectiveness.

In addition, efficient and selective cooling (for heat-based treatments)or warming (for freezing treatment) of the devices is rarely provided.This substantially increases patient discomfort and increases thelikelihood of healthy tissue damage during benign prostatic hyperplasiatreatments. These problems have necessitated complex and expensivetemperature monitoring systems along the urethral wall. Satisfactoryablative prostate cancer therapy using extremely high or low temperaturetreatments cannot be undertaken without effective thermal control of thetherapy device including effective cooling of exterior portions of thetherapy device.

It is therefore an object of the invention to provide an improvedapparatus and method suitable for thermal therapy treatment of tissue.

It is another object of the invention to provide an improved method andapparatus for physically separating mammalian organs.

It is yet another object of the invention to provide an improved methodand apparatus for physically separating human organs for thermalisolation purposes.

It is a further object of the invention to provide an improved apparatusand method for thermal therapy treatment which separates the prostatefrom the rectum.

It is yet a further object of the invention to provide a novel methodand apparatus for thermal therapy treatment that utilizes a fluid toseparate the prostate from the rectum for thermal isolation purposes.

It is a still further object of the invention to provide a novel meansfor dynamic monitoring of the treatment temperature distribution and touse such information to aid in the control of the deposited power leveland its distribution.

It is another object of the invention to provide an improved applicatorwhich can be inserted into a space between a prostate and a rectum andbe positioned with respect to the prostate and maintained in positionduring treatment.

It is a further object of the invention to provide improved control ofboth power level and the distribution of the power deposited in theprostate in a dynamic fashion during thermal therapy which compensatesfor physiological changes (temperature, blood flow effects) that canoccur during therapy and accommodates operator-desired alterations inthe therapeutic energy distribution within the prostate.

It is an additional object of the invention to provide an improvedthermal therapy device which minimizes energy reaching the rectal wallin benign prostatic hyperplasia or prostate cancer thermotherapytreatment.

Other advantages and features of the invention, together with theorganization and manner of operation thereof, will become apparent fromthe following detailed description when taken in conjunction with theaccompanying drawings, wherein like elements have like numeralsthroughout the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a front view of a human prostate and rectum inaccordance with conventional medical knowledge;

FIG. 2 shows a front view of the prostate and rectum of FIG. 1physically separated by a fluid;

FIG. 3 illustrates a side view of a prostate and rectum physicallyseparated by a fluid;

FIG. 4 shows a front view of the prostate and rectum of FIG. 2 showing adevice for providing the fluid and a fluid temperature sensor;

FIG. 5 illustrates a front view of a prostate and rectum separated by amechanical separator including a thermotherapy delivery system;

FIG. 6 shows a side view of the prostate, rectum and mechanicalseparator of FIG. 5;

FIG. 7 illustrates a side view of the prostate, rectum and mechanicalseparator of FIG. 5 and 6 showing thermal therapy application to theprostate; and

FIG. 8 shows a front view of a delivery system constructed in accordancewith one form of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

FIG. 1 illustrates a front view of a human prostate 12 locatedimmediately above a human rectum 14 in accordance with well knownanatomical observations. The prostate and the rectum 14 are separated bya thin facial plane called “Denoviller's fascia” or a “biplane fasciallayer” 16. Denoviller's fascia is composed of two layers of fibrousmembrane tissue in close contact. To kill prostatic cancer cells withinthe prostate 12, the entire prostate 12 must typically be subjected tothe thermal therapy, regardless of whether heating or cooling techniquesare utilized. Because the rectum 14 naturally lies in intimate contactwith the prostate 12 and the biplane fascial layer 16, if one subjectsthe periphery of the prostate 12 to intense thermal therapy to kill allliving tissue within, one risks damaging the portions of the rectum 14close to the prostate 12. Such damage can lead to serve complicationssuch as urethral or vesicle-rectal fistulae.

The present invention can be ultrasound or magnetic resonance or otherimaging modalities to direct the percutaneous (through trans-perinealtechniques or others) instillation of fluid 18 under pressure into thebiplane fascial layer 16 (Denovillers fascia) to create a real space 20from the pre-existing virtual space, thereby physically separating therectum 14 from the prostate 12. Extremely low fluid pressures (i.e.,gravity-fed flows) can be used in accordance with the invention ifdesired. The fluid 18 tracks into this fascial plane, physically andthermally isolating the rectum 14 from the prosate 12, and isolating theprostate 12 from lateral and inferior lying structures (e.g., theperineal diaphragm, sphincteric mechanism and neurovascular bundles).Fluid 18 can be continuously instilled to cool (or warm, as desired) andseparate this space 20 and protect adjacent structures. Thermoprobes canbe placed into the periphery of the prostate to ensure adequatetemperatures to ablate cancer cells while temperature sensors 22 andpressure monitors in the fluid space can dictate the amount of fluidflow necessary to adequately protect adjacent structures. Conventionalintermittent trans-rectal ultrasound can also help ensure adequatecontinuing separation of vital tissues by the instilled cooling fluid18.

In accordance with one preferred embodiment of the invention, a needle24 is inserted at a location near or between the prostate 12 and rectum14 to infuse a fluid 18 for cleaving or providing a space 20 physicallyseparating the prostate 12 and rectum 14. It will be apparent that allof the organ separation methods described herein can be practiced from avariety of entry ports: transperineally, transrectally, transurethrally,suprapubically and others. The fluid 18 can be a cooling solution (ionicor nonionic), an insulating medium (as in energy absorption), an energyreflecting medium for use with some trans-urethral therapy applications,a warming solution, air or a gas, or some type of gel. Infusing thesetypes of agents essentially provides a space 20 to either help insulatethe rectum 14 from the therapy or can provide a means to either augmentthe therapy or to provide the actual therapy itself.

The fluid 18 can be bolused in or continuously infused to provide propermaintenance of the space 20 between the organs and proper temperature ofthe fluid 18. The fluid 18 can also be recirculated into and out of thespace 20 by the use of a multilumen catheter or by use of multiplecatheters. For heat treatments, the fluid 18 can be cooled to providecooling to the rectum 14. Alternatively, the fluid 18 can be maintainedat a minimally therapeutic temperature. Therefore, monitoring of thefluid 18 temperature within the space 20 or in the delivered andreturned solution temperature can be used to guide or enhance thetreatment of effectiveness. For cooling or freezing treatments of theprostate 12, the fluid 18 can be warmed to ensure that the rectum 14 isprovided a safety cushion such that the therapy inside the prostate 12can be as aggressive as possible.

In accordance with another form of the invention, a mechanical separator28 can be utilized to provide this space 20 and remove the need toinfuse or continuously infuse an agent which would either be resorbed bythe body or withdrawn by a physician.

This space 20, once created, can also be used to provide a window withinwhich to now deliver therapy, feedback regarding the extent of thetreatment by providing more localized control or for various types ofimaging (e.g., ultrasound). Further details for implementing thosefunctionalities are described hereinbelow. This technique can beespecially useful for prostate cancer which develops predominantly inthe posterior and lateral edges of the prostate 12. The close proximityof the thermally sensitive rectum 14 to those commonly afflicted areasof the prostate 12 limits the effectiveness of conventional treatment.By utilizing the space 20 or window to now provide a means for directlytreating these regions of the prostrate 12 in a directional way, therectum 14 can be protected from thermal damage, and the location of thecancer can be extremely aggressively treated in a safe and relativelycomfortable manner. Therapy elements (energy sources) capable ofproviding desirably asymmetric energy patterns include, withoutlimitation, laser, microwave (especially with some type of shielding(e.g., air) to avoid heating the rectum 14), cryosurgery, ultrasound(focused or diffuse) and diagnostic ultrasound. The diagnosticultrasound and the therapeutic ultrasound can be combined into the sameprobe if desired.

Suitable mechanical separators 28 can comprise a variety ofconfigurations and materials. For instance, a conventional ballooncatheter 30 can be inserted into the biplane fascial layer 16 andinflated to lift the prostate 12 away from the rectum 14 as shown inFIGS. 5 and 6. Further, any number of mechanical devices can be usedsuch as graspers, expanders, and similar devices. The balloon catheter30 can be inflated with air, water, gel or virtually any other fluid,and the fluid 18 can be either static or continuously recirculated.Alternatively, open-ended devices can be used to both partially orcompletely physically separate and instill fluid. The fluid can beselected to cool the therapeutic element 36 and help separate theorgans. It will be apparent to one of ordinary skill in the art that airor other fluids that do not freeze should be used for freezing types ofthermal therapy treatments.

The balloon 32 can include a nondistensible or infinitely expandable(i.e., latex) structure for creating the desired space 20. Thetemperature of the inner portion of the balloon 32 can be monitored andregulated to a specified temperature. This temperature can also bemodified during a treatment to suit the individual clinical/therapeuticneeds or targets. In this way, either warming or cooling can beadministered as the need arises. This temperature can also be used toensure that the (peripheral) outer portions of the prostate 12 achieve adesired thermal therapy treatment temperature while ensuring that therectum 14 remains at safe, subtherapeutic temperatures.

Temperature sensors 22 can also be added to the outside of the separator28 in various locations including, but not limited to, along the base ofthe prostate 12 and/or along the rectal wall. In this way, more directmonitoring of anatomical structures of interest can be achieved and alltissues can be maintained at desired temperatures. The separator 28 canalso provide a mechanism for treating the outer portions of the gland asdiscussed hereinafter.

For example, the separator 28 can also be used to house a therapeuticelement 36 such as one or multiple lasers, therapeutic ultrasound(focused, directional or diffuse), diagnostic ultrasound or microwaveelements. The therapeutic element 36 can be directional, shielded orsimply conventional. The element 36 can then be used to effectivelytreat the outer portions of the prostate 12. This approach can be usedin conjunction with another form of treatment, either drug or device,and can be used with interstitial or intraluminal treatments. If needed,a conventional endoscope or similar device can be inserted to guide theapplication of the treatment under direct visualization.

The therapeutic element 36 can incorporate a locating means 40 wherebythe location of the treatment can be confirmed, adjusted or maintainedthroughout the treatment. This locating means 40 can include, withoutlimitation, a helium neon laser pointer for direct vision or amechanical/ultrasoun opaque (i.e., metal) indicator on the probe itself.It can also comprise an ultrasound imaging device capable of monitoringthe therapeutic effect in the tissue itself.

While prostate treatment uses of the present invention are describedherein for illustrative purposes, it will be readily apparent that thepresent invention can also be used to treat other anatomical structuresincluding, without limitation, structures inherent or attached to therectum 14 itself (e.g., treating the wall of the rectum 14 or tumorsassociated with the rectum 14).

Thermal therapy delivery systems 50 can also be used as mechanicalseparators 28. The delivery system 50 can take a number of forms, suchas the one described in co-pending U.S. patent application Ser. No.07/976,232, the Detailed Description of Preferred Embodiments which isincorporated herein in its entirety. Alternatively, the delivery system50 shown in FIG. 8 can be used satisfactorily. The delivery system 50can include the ability to provide degassed and temperature regulatedwater flow into the delivery system 50 adjacent tissue to be treated. Anexample of such a suitable delivery system 50 is a single or multiplelumen device which circulates fluid, gas, gel and the like underpressure within a closed environment. The delivery system 50 is intendedto be inserted into body cavities or interstitially. The delivery system50 can be inserted into the body (organ) targeting a specific treatmentsite. The delivery system 50 can house a therapeutic element 36 such aslaser, microwave, therapeutic or diagnostic ultrasound or simply atemperature sensor 22. The fluid 18 or infused agent can be recirculatedunder pressure or can remain static. This form of the invention candeliver therapeutic energy to internal body structures through aminimally invasive procedure.

The delivery system 50 is preferably small in diameter, being 9 Frenchand under. Delivery system 50 as small as 6 French have been usedsatisfactorily and are being further miniamrized. The delivery system 50incorporates 360 degree radial cooling (or warming) which is essentialfor this intensive thermal therapy, especially for interstitial therapy,because it greatly reduces the potential for exit wounds which couldresult from both thermal or freezing technologies.

The delivery system 50 can be made out of extremely thin polymers, suchas PET, which permits the use of very thin wall thicknesses, therebyminimizing the overall device size. This type of material is essentiallynondistensible and can withstand high pressures without failure. Thispermits passage of fluid 18 or other media under pressure to provideflow without compromise of the structure. The delivery system 50 canalso be made from typical catheter materials with the size increasingdue to the need for larger wall thicknesses.

The delivery system 50 can have a rigid structure that aids in insertionor could be made so thin that it essentially has no rigidity. The latterdesign can be inflated to provide the handling and insertion stabilityrequired. This has the advantage of permitting extremely thin wallthicknesses to be used, thereby, maximizing throughput flow and/orminimizing overall size. The rigidity of the delivery system 50 can alsobe used in conjunction with a conventional sharpened tip at one end ofthe delivery system 50. The sharpened tip enables interstitial insertionof the delivery system 50 where desired.

The circulating fluid 18 could be either a cooling agent or a warmingagent, whichever is required for the particular thermal therapy beingutilized. For example, microwave therapy benefits from a cooled devicewhereby the cooling of the antenna provides a substantial increase inefficiency. The delivery system 50 preferably incorporates thetherapeutic elements 36 with complete cooling or warming (viasubmersion) along the therapeutic element's 36 entire length. Thisconfiguration is the most efficient use of space, thereby resulting in asmaller profile.

The outer structure (lumen) 52 of the delivery system 50 can be madeeither nondistensible or moderately to fully distensible. A distensibleouter lumen diameter can be changed even during a treatment to maintaindesired contact with the surrounding tissue. This is important fortherapies that benefit from intimate contact between the applicator andthe tissue for efficient transmission of energy such as microwave,laser, ultrasound and the like.

The change in lumen 52 diameter can be accomplished via an activeincrease in the internal pressure of the delivery system 50. Thepressure can be increased (inflated), decreased or otherwise controlledautomatically (or manually) and triggered via the recording or reflectedor lost power transmission which can be monitored real time. Aconventional pump 60 or other inflation system can be controlledelectronically for this purpose. This can be a feedback circuit toimprove the efficient transmission of energy throughout the duration ofthe treatment. In this way, intimate contact between the delivery system50 and the surrounding tissue can be maintained throughout thetreatment, increasing the efficiency of the energy transmission.

Pressurization can also be a useful feature of the delivery system 50for: clearing the pathway of air or impurities; cooling or warming; andreducing or eliminating modifications in the environment resulting fromthe treatment. For example, in microwave treatments, the cooling mediumis typically a deionized solution such as distilled water. With theapplication of microwave energy, the microbubbles are produced along theantenna resulting in an increase in reflected power. This can developinto an almost total stoppage of emitted energy into the tissue.Pressurization desirably changes the degassing characteristics of themedium and can minimize the effect of microbubbles on energytransmission. Flowing fluid 18 also washes any of the microbubbles outof the energy emitting pathway. Air will block the transmission of mostenergy sources such as microwave and ultrasound. Laser will also seethis as another interface which can result in overheating of thedelivery system 50 in that region possibly resulting in delivery system50 or laser malfunction. Pressurization can therefore reduce oreliminate reflected power and can be varied throughout a treatment tocompensate for changes in the reflected power levels that may occur.

Reflected power will also change according to the matching/mismatchingcharacteristics of the environment surrounding the delivery system 50.This is especially true for microwave energy. Therefore, the measurementof reflected power can be used to correlate with tissue changes in thesurrounding tissue. This measurement can, therefore, be used as afeedback mechanism for the progression of a treatment or for aregulating mechanism during a treatment. It can be used as a surrogatemeasure of tissue temperature, or tissue destruction and can also beused to determine if the treatment is being applied too aggressively.For example, if the therapy is too aggressive, the interface between thedelivery system 50 and the surrounding tissue may change (e.g.,dehydrate) which will impact the matching between the two entities. Theseverity of the mismatch will be reflected in an increase in thereflected power. This mismatch clinically results in a less effectiveadministered treatment. By reacting to the change in the reflectedpower, the aggressiveness of the treatment can be modified to managethis event. Reflected power will change with changes in the temperatureof the environment surrounding the delivery system 50. Accordingly, thismeasure can be used to estimate the temperature of the environment. Thisis the same for actual physical changes in the surrounding environment(e.g., denaturization, carbonization, dehydration, etc.); therefore thismeasure can also estimate effects of a treatment upon the surroundingenvironment.

While preferred embodiments have been illustrated and described, itshould be understood that changes and modifications can be made thereinwithout departing from the invention in its broader aspects. Variousfeatures of the invention are defined in the following claims.

We claim:
 1. A method of providing thermal to prostate tissue of apatient, comprising the steps of: inserting a fluid infusing device intothe patient; locating the fluid infusing device at a location adjacent aportion of the patient's prostate and the patient's rectum to providepassage of a volume of a fluid from the device to said location withouta containment structure between the portion of the patient's prostateand the rectum, said location selected to allow said fluid to beginphysically separating the portion of the prostate and the rectum;continuing to infuse said fluid causing physical separation of theportion of the prostate and the rectum; and applying said thermaltherapy to the prostate tissue.
 2. The method as defined in claim 1,further including the step of containing to infuse said fluid tocompletely physically separate all portions of the prostate and therectum with said fluid.
 3. The method as defined in claim 1, whereinsaid location is disposed in a biplane fascial layer of the patient. 4.The method as defined in claim 1, including the step of delivering thefluid under pressure.
 5. The method as defined in claim 1, including thestep of using a recirculating apparatus to recirculate said fluid. 6.The method as defined in claim 1, and including the step of positioningthe temperature sensor to be disposed in contact with said fluid.
 7. Themethod as defined in claim 1, wherein said fluid cools the rectum. 8.The method as defined in claim 1, wherein said fluid is a liquid.
 9. Amethod of providing thermal therapy to prostate tissue of a patient,comprising the steps of: providing a gel to a location adjacent aportion of the patient's prostate and the patient's rectum, saidlocation selected to allow said gel to begin physically separating theportion of the prostate and the rectum; said gel causing physicalseparation of the portion of the prostate and the rectum and applyingsaid thermal therapy to the prostate tissue.
 10. A method of providingthermal therapy to prostate tissue of a patient, comprising the stepsof: inserting a fluid infusing device into the patient; locating thefluid infusing device at a location adjacent at a portion of thepatient's prostate and the patient's rectum to provide passage of avolume of a fluid from the device to said location without a containmentstructure between the portion of the patient's prostate and the rectum,said location selected to allow said fluid to begin physicallyseparating the portion of the prostate and the rectum; continuing toinfuse said fluid causing physical separation of the portion of theprostate and the rectum; applying said thermal therapy to the prostatetissue; and using a temperature sensor to sense temperature of thevolume of fluid to minimize damage to the prostate and to the rectum.